Help needed - slightly weeping nasa log skin fitting

[tomdmx]

Hi All, day after the re-launch of our steel yacht I've noticed a slight weeping from the nasa log skin fitting...its an older one and appeared fine (we did not touch it) and now its weeping...

It started with a leak from the blanking cap which we've tightened up but in doing so we also moved the bottom nut..so we have had to tighten that up a bit and used a silicon sealant (not sika) on the outside of the nut (but inside the boat)...now it seems to be very slightly weeping (not sure from where actually ie blanking cap or bottom nut)...and when I mean weeping its moist to touch and a small drip is visible over a period of 24hrs or so on the bottom but that's it (thought I know these things can only get worse)

So am I looking at another lift or is there a way to fix it in the water (ie epoxy or silicon?)..I am a diver so can dive and someone from the yard suggested I go for a dive, use CT1 silicon and run a seal from the outside (apparently it works under water)

 

[Appledore]

Hi,

There has been a recent thread similar to yours.

If I remember correctly, the NASA installation instructions say you should 'glass-in' the retaining nut on the inside of the hull. Some folk have stated that the through hull fittings are sometimes prone to cracking themselves, hence the need for the epoxy or whatever you can use. I wouldn't recommend over-tightening the retaining nut for this reason. Best to play safe. Further, I have a dedicated wooden bung on a string to plug the tube if anything does go wrong!

 

[SAMYL]

Lifting out would be a hassle. Your idea of using CT1 is perfectly fine and will work well, it does stick underwater, but don't put too much on. Make sure the outside is well cleaned of slime etc. first. It will do fine 'till your next lift.

 

[tomdmx]

Yep got the wooden plug also Its not glassed from the inside, so just reading the post I think a CT1 job outside and glassing it inside...we just went in the water (2 days ago) so hopefully not a lot of slime etc...and our next lift is south of France approx 3 months away, so with any luck it will be ok till then...

 

[Appledore]

Yep got the wooden plug also Its not glassed from the inside, so can I glass it in or will the weep be persistent through the glass also?

Epoxy resin sets quite rapidly, so, as long as it's a very minor weep, and you can get the surrounding area of hull bone dry, I'd go for it. Once set, the water won't get through! (Well, I don't think it will!!).

 

[pete]

If all you did was to turn the complete fitting slightly in the hull and it has started leaking and there is no chance that you have split the fitting and it is only leaking as little as you say I would wrap it inside with a towel monitoring it regularly and wait for your next lift out to remove the fitting and refit it properly anything else will most likely be a bodge job that will make doing it correctly later on that bit harder I can't see any reason why it should start to leak worse if you don't disturb it.

As you probably know the seal is made outside the hull not on the inner nut and sealing the edges of the inner nut may just divert the water up the nut thread.

Pete

 

[l'escargot]

There is a very strong possibility that the fitting is cracked across a thread - it is a known issue with fittings not glassed in. If it is, tightening the nut down actually opens the crack more and increases the risk of the whole fitting snapping off in your hand - I've been there, fortunately when the boat was out the water. Do examine the fitting closely.

Do a search on the forum, there are threads back to 2004 at least. One thing to note is that silicon sealant is recommended and not sikaflex which can cause the fitting to degrade and become brittle.

 

[uxb]

When I bought my current boat there was signs of weeping around both the depth and log through- hulls. ( something else the imbecile of a surveyor missed...)
When I got the boat out the water I found both transducers nipped up almost hand tight and bedded in with string and grease.....

 

[Baggywrinkle]

I started a similar thread a few months back ...

http://www.ybw.com/forums/showthread.php?t=311797

Unfortunately it was a haul out and re-seal in the end, the pressure behind anyting I tried to seal it with just pushed back through before it cured.

Wish you better luck than I had.

 

[macnorton]

An old trick that was used with wooden boats was to tip sawdust in the water around the area of the leak, I tried this on a GRP boat with a slight sterndrive leak and it cured it. worth a try?

 

[KellysEye]

If you can't stop the leak use under water epoxy that is green and white and comes in a tube. Keep squeezing it with a wet hand until it turns white, apply and hold it tight with a wet hand until it dries, about ten minutes.